1. Technical Field of the Invention
The present invention pertains in general to cellular telephones and devices which use cellular telephones for mobile communication, and more particularly, to the connection of a portable computer via a modem to a cellular telephone.
2. Description of Related Art
The growing use of cellular telephones and accessory devices such as speakerphones, portable computers, and portable facsimile machines is allowing many people to perform their jobs while away from their home and office. In particular, the use of cellular data modems in conjunction with laptop computers allows people to receive and send facsimiles and access local area networks while in a mobile office environment.
A shortcoming of sending and receiving facsimiles via a cellular telephone is that the modem must be repeatedly connected and disconnected, to and from, the cellular telephone when the user wishes to send or receive a facsimile or place or receive a voice telephone call, respectively. Furthermore, in situations where a user does not know when an incoming facsimile will be transmitted, the user must keep the modem connected to the cellular telephone. Maintaining this connection disables voice calls and prevents the cellular telephone user from using the cellular telephone to place or receive voice calls. Repeated connecting and disconnecting of the modem is especially bothersome for users while driving an automobile when the user's hands are not readily available. Besides being bothersome, this distraction is also dangerous to the user while driving an automobile.
There currently is no acceptable method by which a user of a cellular telephone can place and receive voice calls without physically disconnecting the modem from the cellular telephone. Generally, a cellular telephone user who wishes to avoid connecting and disconnecting the modem when making voice calls is forced to use two separate telephones with different telephone numbers. There is a need, therefore, for an interface system capable of connecting a plurality of accessories, including at least a modem, to a radiotelephone and coordinating access by these devices to the audio channel of the radiotelephone without manual intervention by the cellular telephone user. It would also be advantageous for such an interface system to allow the user of the cellular telephone to prioritize operation of the various accessories connected to the cellular telephone.